Automatic telephone system



Aug. 25, 1925. 1,551,170

W. T. POWELL AUTOMATIC TELEPHONE SYSTEM Filed Dec. 13, 1920 IHTERRUFWEW'Z INVENTORI \NIHFRED T POWELL ATTORNEY Patented Aug. 25, 1925.

. YHCARLSON TELEPHONE CORPORATION or NEW Your; f

AUTOMATIC TELEPHONE sys'rinvr.

Applicationfiled December 13, 1920. Serial 110,430,163

To all whom it mag concern: 3 i

*- Be it known that I, WINFREDJT. POWELL,

a citizen of the United States, residing at Rochester, in the county of Monroe and 5 State of New Yorlghave inventedl certain new and useful Improvements in Automatic Telephone Systems, of which the following is a full, clear, concise, 'and exact description. This invention relates to automaticitelephone systems and more particularly to telephone systems employing automatic switches in establishing connections between :calling and wanted subscribers. I 1 In former telephone systems employing an individual non-numerical switch with separate operatingmeans for'each line itwas customary 'to control the motor magnet by a plurality ofcontrolling relays orelectromagnets." It 'isone 'of the purposes'of this invention to provide an individual .nonnumerical switch for each line-in which 'the motormagnet iscontrolledby a single controlling relay; a Also in'automatic'telephone systems where auton'iatic machine interrupted ringing current is provided, it frequently happens that the wanted linelis seized during the silent interval of the interrupter so that; an 1 appreciable interval of time intervenes between-the seizure and signallingrofithis wantedline. In accordance with oneot the featuresfof this invention, means are Eprovided whereby a preliminary impulse .of uninterrupted signalling currentis applied to the called line when this line is seized during the silent interval vof the ringing inter rupter 1 i Referring to the drawing, the single figure represents a portion" of a t'elephone-sys tem employingthe present inventions hThat port-ion of the drawing appearing abovesand 1 to the left of the dotted lines representsa calling s'ubscribers sub-station circuits and elephone 11 11; and the circuitsof the indifvid ual non-numerical 1 switch I of this line. In't-he'lower left ha'nd corner or the drawing tliere appease device herein referred to as ja tdouble interrupter which -is provided :tor theconimon use of allnumericahswitches em loyed- 1a the exchange. "At' =tl1eright or the dotted "line there isdiagrammatically xrepresentedjthe operating circuits of a cor-1 nectoriswitch. -Although no selector switches have been represented, it will vbe understood that one or more of such switches may be interposed'in the circuits in the broken l nes connecting the circuits of the individual line switch and the connector switch, it the invention is used in large systems.-

The individual line switchfimayi be of the mauurao'runme oorrr'ANY, or nocnns'rnn, NEW coa A structure similar-to that disclosed in the patent to (Element 1,107,153,;Augustt11, 1914 and the circuits ot this switch are so arrangedvthat the switch, when notin use, re tains its brushes in engagementewiththe trunkl circuit last used. The connector i switch may be similar in structure to that disclosed in the patent to Keith et al 815,- 176, March 13, 1906, when modified to operate in a so-called two-Wiretelephoneisystem.

The double interrupter is preferably of the formzof'a constantly rotating shaft provided w1th two. interrupting devices so arranged that they a close their circuits in predetermined'time intervals as diagrammaticallyindicated-in-th'e drawing.

'" The single relay at atheeline switch is provided with 'a jsingle core and three electromagnetic windings; The lower winding of the relay 5is separated from theupper windin'g i'ot this relay bya strip offconduoting material whichserves as a common portion jfor thej electromagnetic circuit, .including'the upper 5 armature of this relay and 1 is also included in the electromagnetic circuit extending through the lower armature 8 of this relay: This=relay isalso provided with two armatures, thefirst of which 8-is pivoted at its -middle point and is provided atone of {itsends with a hook 21. This armature is controlled by' the; lower electromagnetic winding "of" relay 5 which windinghas an electromagnetic circuit, distinct, from the upper-two windings of this relay. The; ar-

*Inature QO "of the relay 5 is arranged to be attracted byeither otthe-upper wind'- ings of the relay 5, both of which have sub stantially the same electromagnetic circuit, When the armature- 20' isuactuated= afterthe "armature 8 hasibeen operated, a all of the c'ontact! springs; such as; 23, QLand; 55,? will be closed, while the ,c'ontacts 6 F7 andi22 will,

opened; fAlso if the armature 8 is retracted when the arniatureQO is in its operatedi position, this last mentioned armature will be mechanically locked operated until such time as the armature 8 is again attracted. If, however, the armature is attracted when the armature 8 is in its normal position,

then the hook 21 will prevent a complete seriously efiecting the operation of the systom. It is believed that the invention will best be understood by describing the method of establishing a telephone connection between a calling subscribers sub-station indi- 'cated at A, to a wanted subscribers'substation indicated at B. Whenthe subscriber at A initiates a call by removing his receiver from its switch hook, a circuit is closed through the lower winding of relay 5,

i conductor 56, contact springs 6 of this relay, through the lower side of the calling line and the sub-station circuits in series, overthe upper-side of the calling line, spring con- 4 tacts 7 of relay 5, to ground. The lower winding of the relay 5 is energized and causes this relay to .attract its armature 8 to close the contact springs controlled by it. The upper armature of relay 5' remains inactive at this time. As soon as the armature. 8 is attracted, a circuit is closedirom grounded battery, resistance, back contact, armature and Winding of the motor magnet 9, contact springs 10, to ground. Under the control of this circuit, the motor-magnet 9 advances the brushes 11, 12, 13 and 14 of the line switch to hunt for an idle trunk line to the succeeding numerical I switch. Busy trunks are characterized bythe absence of potential on their test terminals, such as 15 so that/as long as the test brush13 is testing busy trunks, the motor magnet 9 continues to advance its brushes, but when this test brush engages an idle. trunk, a, circu it is closed from ground, atthe armature and back contact of relay '16, right-hand winding of relay 17, side switch wiper- 18 infits first position, test terminal 15,:brush 13, contacts 19, middle winding of. relay 5,

armature and back contact of motormagnet 1 9, resistance, to groundedbattery.

-*Thi's lastdescribed circuit'is effectiveto shunt the'motor magnet 9 and to'energize 'the'middle winding of relay 5, causing it to attract the upper armature20 of this relay.

As soon 'asthe armature 20. is fully operated, it opens the circuit through the lower winding of the relay 5, at contact springs 6 and 7, so that the lower armature 8 of this relay is retracted and the hook 21 engages the free end of the armature 20, thus locking this armature operated. Also when armature 20 is operated, it opens the contacts '22 and close contacts 62 to ground, whereby the seizure of thecalling line by any connector switch is prevented. The operation of armature 20 likewise closes contacts 23 and 24 thereby connecting the calling line with its line brushes 11 and 12 to complete an energizing circuit extending from battery, through both windings of the impulse relay'l6 in series. As long as relay 16 attracts its armatures, it closes a circuit from ground, its right-hand armature and front contact, right-hand winding of relay25, to grounded battery. With relay 25 actuated, a circuit is closed from grounded battery, armature and back contact of release magnet 26, resistance 27, conductor 28, winding 29 of the'escape magnet, side switch wiper 30 in its firstposition, outermost front contact and armature of relay 25, conductor 31, contacts 32, to ground, when these contacts are closed bythe #2 interrupter, in

its cycle of operation. When this lastdescribed circuit is opened, at contacts 32, by the continued rotation of interrupter #2, the escape magnet deenergizes and advances its side switch wipers into their second position. c c

The numerical switch is now in condition to receive directive impulses from the dial sender at the calling sub-station and, since it has been assumed in this disclosure that only connector switches are employed, the calling subscriber will operate his dial sender in accordance with the tens digit of the wanted number. In response to each of these impulses, the impulse relay 16 will vibrate its armatures thereby closing an operating circuit' forthe'l primary motor magnet 33erstending from grounded battery, winding of this magnet, side switch wiper 18, in its second position, winding ofthe'change-over relay'v 17 back contact and armature of the impulse relay 16, to ground. 1 In response to the first retraction of the armature of relay 16, the rimary motor magnet 33 advancesthe brus cs 34, 35 and 36 of the connector switch one-step .in the primary-direction.v Also the escape magnet 29 ,is energized in a circuit now traced: from grounded battery, righthand armature-and back. contact of magnet -26,=resistance 27, conductor.28,swinding of theescape magnet 29, side. switch wiper 30 in its second position, right-hand windingof change-over relay 17, back ,contactand right- "hand armature of relay 16, to ground.

When. the relay 16 attracts its armature after this first'impulse, the escape, magnet de energizes and advances the side switch wiper into their third position, but the operating circuit of the primary magnet 33 is still maintained closed in the third position of the side switch wiper 18 so that the remaining impulses of the tens series are repeated to the primary motor magnet causing it to advance the connector switch to select the group in which the wanted line terminates. It should be noted that during the transmission of these directive impulses that the release of the connector switch is prevented by the control of the so-called double interrupter device. During the transmission of these properly timed impulses the release relay 25 will be operated either by an energizing circuit extending through its right-hand winding and controlled at the impulse relay 16 or is locked operated in a circuit, through its left-hand winding and front contact and completed at the armature and back contact of impulse relav 16 and the contacts 37 of the #1 interrupter whenever a release circuit would otherwise be completed from grounded battery, through the left-hand winding of the release magnet 26, the side switch wiper 38, outer back contact and armature of relay 25, conductor 31, contacts 32 of the #2 interrupter togro'und. It will thus be seen that the release of the connector switch is prevented during the transmission of directive impulses. It will subsequently be pointed out how the release of the connector switch is elfected.

At the close'of the tens series of impulses, the impulse relay 16 maintains its armature attracted for a relatively long interval so that the energizing circuit through the right-hand winding of change-over relay 17 is opened. In the event that the contacts 37 of the #1 interrupter are closed, the

relay 17 will be maintained energized through its left-hand winding, front contact and armature. In the course of the operation of the double interrupter-,however, contacts 37 will be opened and when contacts 32 of the interrupter #2 are sub sequently closed, a circuit is completed from ground through these contacts, conductor 31, armature and back contactof change over relay 17, side switch wiper 30 in its third position, escape magnet29, conductor 28, resistance 27 back contact and armature of relay 26, to grounded battery. As the double interrupter device continues to rotate, contacts 32 will be'opened and the escape magnet 29 i will advance the. side switch Wipers into their fourth position.

The connector switch is now in condition to receive the directive impulses corresponding to the units digit of the wanted number. In 1 response to these impulses the impulse relay 16 vibrates its armatures and at its right-hand armature, and back contact closes a circuit from ground, through the righthand winding of change-over relay 17, side switch wiper 18in its fourth position, winding' of the secondary motor magnet 39, to

grounded battery. The escape magnet 29 is energized in multiple with this last described circuit and, when the impulse relay 16' attracts its armatures at the close of the first units impulse, the escape magnet 29 deenergizes and advances its wipers into their fifth position, but the operating circuit of the secondary motor magnet 39 is still. extended through side switch wiper 18 in its fifth position so that in response to the units impulses the connector switch brushes are directively operated to select the wanted line in the previously selected group.

At the close of the units series of im pulses, the impulse relay 16 mainta-ins its armature attracted so that the right-hand winding of the changeover relay 17 is deenergized and subsequently, after an interval determined by the double interrupter device, the circuit through the left-hand winding of relay 17 is opened permitting this relay to retractits armatures to close a circuit from grounded battery, armature and back contact of release magnet 26, resistance 27, conductor 28, escape magnet 29, side switch wiper 30 in its fifth position, back contact and armature of changeover relay 17, conductor 31, contacts 32, to ground. As soon as the contacts 32 are opened, the escape magnetdeenergizes and moves the side switch wipers into their sixth position.

The connector switch brushes are now in engagement with the terminals of the wanted line so that, when the side switch wipers are moved into position 6, the testing of the wanted line is accomplished. Let itfirst be assumed, that the wanted line is idle under which assumption a full battery potential will be present on its test terminal 44:, so that when the connector test brush 36 engages this test terminal, the release magnet 26 will not be operated, but, after an interval measured by the double interrupter device, the escape magnet is energized in the circuit previously described as extending through side switch wiper 30. and conductor 31. When contacts 32 of in terrupter' #2 are opened, the escape magnet moves its side switch wipers into their seventh position; i A

It now becomes necessary to signal the wanted subscriber and in accordance with one featureof the present invention a preliminary impulse of uninterrupter current isjapplied to the wanted line before the interrupted machine ringing current is con nected' tothis line. This; uninterrupted alternating current is applied to the called line in a circuit traceable from grounded battery, through the resistance 45 and ringing generator GEN, lamp 4-6, conductor 17, side switch wiper 42, in its seventh position, connector brush-35, through the lower side of the wanted subscribers line, through the ringer at this station over the upper side of this line, connector brush 34, side switch wiper 41 in its seventh position, to ground. This uninterrupted ringing current will be applied over the circuit just described until the side switch wipers are advanced into their eighth position. This is accomplished when the contacts 32 of the interrupter are again closed to: complete a. circuit from ground, over conductor 31, armature and back contact of change-over relay 17 side switch wiper 30 in its seventh position, escape magnet 29, conductor 28, resistance 27, back contact and armature of release magnet 26, to grounded battery. The escape magnet 29 is energized in this circuit and, when contacts 32 are opened, the side switch is advanced into! position 8 in which position the escape magnet is energized in a circuit traceable from, ground, side switch wiper 30, escape magnet 29, conductor 28, resistance 27, back contact and armature of release magnet 26, to grounded battery. In position 8 interrupted ringing current is applied over a circuit extending from grounded battery, resistance 45, ringing generator GEN, ringing interrupter brush 48, lamp 49, conductor 50, winding of the trip relay 51, side switch wiper 42 in its eighth position, through the sub-station circuits, as previously described, side switch wiper 41, in its eighth position, to ground. The trip magnet 51 is not energized in this circuit but, when the called party responds, the trip relay 51Iis actuated and at its armature and front contact short-circuits the escape magnet29 causingit to release and advance the side switch wipers into the ninth or talking position.

Talking current for the calling subscriber is supplied through the windings of the impulse relay 16 while talking battery for the called subscriber is supplied through the windings of the relay 52.

Let it be assumed that the wanted line was engaged at the time it was tested with side switch wiper 43 in position 6. Under this assumption the release magnet 26 is operated in. a circuit completed from grounded battery, its left-hand winding, side switch wiper 43 in its sixth pos:ition,test brush 36, test terminal 44 and through a multiple test terminal such as 44 and the test brush such as 36 of the connector switch which has previously seized the wanted line through a side switch wiper similar to 43 in position 9, to ground. The release magnet is :energized and closes a locking circuit for itself from grounded battery, through its right hand armature, front contact and winding, front contact and armature ofimpulse relay 16, to ground. At the inner left-hand armature and front contact of relay 26' abusy tone is applied from a source of busy tone current IBZ to the calling sub-scribers line to informhim that the wanted line is busy. The gcalling subscriber then fireplaces his receiver on its switch hook to effect the release of the established connect-ion. The manner of effecting the release operation is the same irrespective of whether the call is abandoned or whether the call has been terminated.

On the restoration of the calling receiver to its switch hook, the impulse relay 16 retracts its armature and, at its inner right hand armature and front con-tact interrupts the locking circuit of the release magnet 26. This magnet, however, is slow in releasing its armatures and a circuit is thereby completed from ground, outer right-hand armature and back cont-act of relay 16, outer left-hand armature and front contact of release magnet. 26, conductor 54, release brush 14 of the line switch, contacts 55 of relay 5, conductor 56, lower winding of relay 5, to grounded battery. The energization of the lower winding of relay 5 causes it to retract its armature 8 which causes the hook'2l to disengage the free end of the armature 20 and, since the calling party has terminated the call, the armature 20 is retracted. It will be recalled that the line switch is of that type in which the line switch brushes remain in engagement with the trunk circuit last used, but these brushes are disconnected from the subscribers line.

On the opening of the locking circuit of release magnet 26 it deenergizes and. restore-s the connector switch as well as the side switch into normal position. The apparatus is IIIIOIW in condition for use on a succeeding ca In the event that the subscriber at A is the wanted party, whenever a connector switch engages the test terminals 57 of this line, a circuit is closed from grounded bat-- tery, back contact and armature of motor magnet 9,. upper winding of relay 5, contact springs 22, contact 57, through a side-switch wiper similar to 43 (shown at the extreme right of the sheet) in its ninth position, to ground. This operates armature 20, but the hook 21 prevents the full attraction of this armature so that, while the lower winding of the relay 5 is disconnected from its line, the line switch brushes 11 and 12 are not connected to the called'st-ation.

It will thus be seen that anon-numerical switch circuit of the stay-put type with only one controlling relay has been provided. Likewise, novel means have: been provided for signalling a wanted subscribers line.

. VVl1at is claimed is: I

1.- In a telephone system, an incoming circuit, a plurality of outgoing circuits, a non-numerical switch for inter-connecting said. incoming circuit with a-ny of said outgoing circuits, operating circuits for said switch wherebysaid switch may occupyany one of aplurality of normal positions when not inuse, a motor magnet for'operating said switch, and a single electroniagnetic device at said switch cooperating with said circuits for controlling saidmoto'r magnet, said electromagnetic device having af single core and "a plurality of interacting armatures. I

2. In a telephone system, an incoming circuit,'*a plurality of outgoing circuits, a non numeric'nl switch for interconnecting said incoming circuit with any ofsaid'outgoing circuits, operating circuits for said switch arranged so that itmay occupyany one of a plurality of normal positionswhen not in use, z't'motorniagnet for operating said switch, and asingle electromagnetic device at. said switch for controlling said motor magnet, said electromagnetic device having a single core and a pluralityof windings; a i

3. In a telephone system, an-incoming circuit, a plurality ofoutgoing circuits, a non-numerical switch for interconnecting said incoming circuit with any one ofsaid outgoing circuits,- a motor magnet for operating said switch, and a single electromagnctic device at said switch for controlling said motor magnet, said electromagnet having a single core and a plurality of windings, one of said windings being energized over both sides of said incoming circuit in series to effect the operation of the motor magnet and a second winding for disconnecting said electromagnet from said incoming circuit and to stop the operation of said motor magnet.

4. In a telephone system, an incoming circuit, a plurality of outgoing circuits, a non-numerical switch for interconnecting said incoming circuit with any of said outgoing circuits, a motor magnet for advancing said switch, said switch having brushes, and a single relay with a single core for controlling said motor magnet, said relay having one winding energized over both sides of said incoming circuit in series to start the operation of said motor magnet and a second winding for disconnecting said relay from said incoming circuit and for connecting said incoming circuit to said switch brushes.

5. In a telephone system, an incoming circuit, a plurality of outgoing circuits, a switch for interconnecting said incoming circuit with any one of said outgoing circuits, a motor magnet for advancing said switch, and a single relay at said switch for controlling the operation of the motor magnet, said relay being provided with two armatures the first of these iarmatures being efifective to mechanically lock the second armature in operated position when once actuated, said first armature operating to start saidmot or magnet and the second armature being effective to prevent opera tion of said motor magnet, and means for operatingsaid -rel'ay toractuate said armatures.

' 6. In a telephone system, an incoming circuit, a plurality of outgoing circuits, a switch having brushesnormally disconnected from said'incoming circuit for connecting said incoming circuit to any one of said outgoing circuits, a motor'magnet for advancingsaidswitch, and a single relay at said switch for controlling the operation of the motor'magnet, said relay being provided with three windings, the first winding being energized over said incoming circuitto start the operation of th'e-m0t0r'magnet, said sec ond winding being energized toconnect said incoming circuit to said switch brushes and said third winding being 'efi'ective to prevent the operation of themotor magnet without connecting said 'incomingcircuit to its brushes/ 7. In a telephone system, an incoming circuit,'a-plurality of outgoing circuits, an automatic switch having brushes normally disconnected from saidincoming circuit but effective to connect said incoming circuit with any of said outgoing circuits, a motor magnet for advancing said switch, and a single electromagnet at said switch for controlling the operation of the motor mag net, said electromagnet being provided with magnet and the second armature controlling the connection of said incoming line to the brushes of said automatic switch.

8. In a telephone system, an incoming circuit, a plurality of outgoing circuits, an automatic switch having brushes normally disconnected from said incoming circuit but operating to connect said incoming circuit with a selectable outgoing circuit, means for characterizing outgoing circuits by a nonselectable condition, a motor magnet for advancing said switch, a test circuit for determining the selectable condition of an outgoing circuit, operating to controlthe motor magnet, and a single electromagnet at said switch for controlling the operation of the motor magnet, said electromagnet being provided with a single core and a plurality of armatures, one of said armatures controlling the motor magnet and said test circuit and the second armature operating to connect said incoming circuit to the brushes of said automatic switch.

9. In a telephone system, a plurality of telephone lines, switches for interconnecting said lines, directively controlled means in cludinga uni-directional rotating timing device oontrolled over one of said telephone lines for selectively operating anumerical switch to select a wanted telephone line, sources of signalling current of two difierent characters, and means controlledby said timing device for connecting. said sources of current to a wanted telephone-line.

10. In a telephone system, .anincoming line, a plurality of outgoingtelephone lines,

means including a numerical switch for interconnecting said v incoming line with a wanted outgoing line, means controlled over said incoming line for variably operating said numerical switch, and a unidirectional rotating timing device cooperating with said means in the control of said automatic switch, sources of interrupted and non-in terrupted signalling current and means under the control of said timing device for connecting said sources ofcurrent in sequence to the selected telephone line.

11. In a telephone system, an incoming circuit, aplurality of outgoing circuits, a non-numerical switch for interconnecting saidincoming circuit with any of said outgoing circuits, said switch having at' least four brushes, a motor magnet for advancing the brushes of said switch, a single relay with a single core controlling said motor magnet, said relay havingone winding energized over both sides of said incoming circuit in series to cause the operation, of said motor magnet, said relay having a second winding for disconnectingsaid relay from said incoming circuit and for connecting said incoming circuit to certain of said switch brushes, said relayhavi-ng a third winding for restoring said switch to its normal condition and circuits for said last two relay windings completed through the certain others of said switch brushes.

12. In a telephone-system, an incoming circuit, a plurality of outgoing circuits, a switch for interconnecting said incoming cir cuit with any of said outgoing circuits, a motor magnet for advancing said. switch, and a single relay at said switch for controlling the operation of the motor magnet, said relay being provided with two armatures to control the operation and restoration of said automatic switch, magnetic circuits in said relay for controlling said armatures, and a common conducting portion for said magnetic circuits.

In witness whereof, I hereunto subscribe my name this 4th day of December A. D. 1920.

WINFRED T. POWELL. 

